The present invention relates to a clutch and a motor.
Japanese Laid-Open Patent Publication No. 2001-336550 describes an example of a motor used for a power window or the like installed in a vehicle. The motor includes a motor unit, which has a rotation shaft that is rotated and driven, and an output unit, which has a worm to which the rotation of the rotation shaft is transmitted and which outputs the rotation transmitted to the worm. A clutch (coupling portion) connects the rotation shaft and the worm. The clutch functions to transmit rotation drive force of the rotation shaft to the worm and not to transmit rotation force from the worm to the rotation shaft.
The clutch includes a coupling member that rotates integrally with the rotation shaft, a driven rotor that is rotatable integrally with the worm and engageable with the coupling member in the rotation direction, and a tubular clutch housing into which the coupling member and the driven rotor are inserted. Further, rollers are arranged between an inner circumferential surface of the clutch housing and the driven rotor. The rollers restrict rotation of the worm when held by the inner circumferential surface of the clutch housing and the driven rotor when the rotation shaft is not rotated and driven. The rollers are supported by a support inserted into the clutch housing. When the rotation shaft is rotated and driven, the support is pushed by the coupling member in the rotation direction and rotated with the rotation shaft.
Grease is applied to a predetermined portion of the clutch such as the inner circumferential surface of the clutch housing so that the clutch operates smoothly. In the clutch, since the coupling member and the support are inserted into the clutch housing, the grease applied to the inner circumferential surface of the clutch housing may collect on the coupling member and the support. Further, the coupling member and the support rotate with the rotation shaft when driven and rotated. Thus, the grease that collects on the coupling member and the support may be moved to the radially outer side by centrifugal force and leak through an opening of the clutch housing out of the clutch. When grease leaks out of the clutch in such a manner, the amount of grease becomes insufficient. This adversely affects the operation of the clutch. For example, when restricting rotation from the worm, it may be difficult to hold the rollers between the inner circumferential surface of the clutch housing and the driven rotor (that is, rollers slip on inner circumferential surface of clutch housing).